Although the use of cloning to produce copies of humans has been suggested, many people would judge this to be morally wrong. In addition, the prospect of cloning humans raises false expectations, since human personality is only partly determined by genes. Cloning a sick or dying relative would provide a genetically identical copy of that person, but this new individual would likely develop a quite different personality. Similarly, a copy of an athlete, movie star, or scientist might well choose another career because of chance s during his or her lifetime. One hypothetical scenario involves a childless couple who wish to make a copy of one or the other partner rather than having a child by artificial insemination (授精). The social concern is that the parents would not be able to treat naturally a child who was a copy of one of them. The impetus(推动力) behind the research that led to Dolly was not to find a way to clone humans but rather to develop genetically engineered animals that would serve a variety of purposes. As there are great genetic differences in cattle herds and sheep flocks, breeding copies of selected livestock would increase the efficiency of agricultural productivity and help improve the quality of such commercial products as milk, beef, and wool. As in the management of other breeding schemes, it will be important for scientists to maintain the balance between intense selection of livestock and the maintenance of genetic variability. Preservation of frozen cells from a large number of representatives of different breeds would allow nuclei from those donor cells to be used as required. The ethical issues in animal cloning are perhaps less controversial than with humans; nevertheless ,some people worry that producing large numbers of animal clones only increase the likelihood that these animals will be mistreated. Genetic modification of livestock will also provide new opportunities in medicine and research. Today many patients in need of transplants die before organs become available from suitable donors. Cloning pigs has been suggested as a means of rapidly achieving xenotransplantation (异种移植), the use of animal organs to replace organs in human patients. Organs transplanted between species are in er of being destroyed within minutes by the acute immune response of the body receiving the transplant; however, strategies are being developed to modify pigs genetically so that rejection by the immune system may be effectively pred. 31.According to the passage people object to the use of cloning to produce copies of humans mainly because _________. A.its technique is not good enough B.it is immoral and leads to wrong expectations C.it may lead to parents' unnatural behavior. to the copy of them D.it may lead to many people' s unemployment 32.Which of the following words can be used to replace the word "well" in Para. 1, Line 6? A.easily B.as one would wish C.quite possibly D.skillfully 33.In breeding copies of selected livestock, scientists should take into consideration of all the following aspects EXCEPT_________. A.the balance between extreme selection of livestock and continuation of genetic variability B.ill-treatment of the copied animals C.preservation of frozen cells D.intense opposition to animal cloning 34.What do you think would be described in the next paragraph of the passage? _________. A.The strategies to modify pigs genetically. B.People's response to the proposals above. C.The immune system. D.Another potential medical application of cloning. 35.What is the author's attitude towards the technique of cloning? _________. A.In favor of cloning both animals and humans. B.In favor of cloning animals but not humans. C.In favor of cloning humans but not animals. D.In favor of neither cloning animals nor humans.